There currently are no uniformly accepted clinical, neuroimaging, or laboratory outcome measures for clinical trials for the treatment of HIV associated neurocognitive disorders (HAND). The goals and objectives of this Core are: 1) to provide the resources necessary to continue a clinical cohort of well-characterized HIV+ and demographically-matched HIV- individuals for studies evaluating new outcome measures and surrogate markers for clinical trials of HAND, 2) to liaise with other NIMH Centers or other funded IPCPs involved in NeuroAIDs therapeutic work to help identify potential candidate agents, 3) to provide the resources necessary to design and conduct small pilot studies to evaluate potential novel compounds to treat HAND, 4) to maintain a data infrastructure to allow for efficient querying of clinical and laboratory data, 5) to provide statistical support for studies involving the Center Grant resources, 6) to provide a resource for linkage with ongoing Neuro-AIDS trial consortia. The Clinical Outcomes Core provides support for a cohort of 150 HIV+ and 50 HIV- individuals which is used to evaluate both neurocognitive and novel functional assessments. Stored CSF and blood specimens from cohort participants are used to validate surrogate markers. Participants with a well characterized HAND stage from the Clinical Outcomes Cohort are used for developmental projects. The Core also evaluates safety, tolerability, and efficacy outcome measures for new compounds for the treatment of HAND. Thus, the Core provides a service to develop improved outcome measures for use in clinical trials, and obtains preliminary data for candidate drugs of safety and tolerability. The Core will also obtain data to determine the sample size needed for larger, confirmatory studies of efficacy.